Allergic sensitisation in south africa: allergen-specific ige-component testing (isac)

Background: Allergic sensitisation patterns differ globally; therefore it is important to understand local South African sensitisation patterns to inhalant and food allergen components to enable clinicians to diagnose and manage South African patients appropriately. Methods: A retrospective study was conducted reviewing component allergen testing data from a private laboratory provider in South Africa over a two-year period. Data generated from all Immuno Solid-phase Allergen Chip (ISAC) tests referred from all regions in South Africa were collected and analysed according to the allergen-component positivity rate. Results: A total of 813 consecutive patients were tested for allergen-component sensitisation by ISAC testing. Data were assessed to determine the most prevalent sensitisation patterns for inhalant, food and cross-reactive allergen components. The most frequent inhalant allergen components were Bermuda grass (Cyn d 1) and Timothy grass (Phi p 1), followed by cat uteroglobin (Fel d 1) and house-dust mite (HDM) (Der f 1). Peanut (Ara h 2), shrimp (Pen m 2) and egg white (Gal d 1) were the most prevalent food-component allergens. The most common pollen-food cross-reactive allergen components were cross-reactive carbohydrate determinant (CCD), profilin and thaumatin-like protein (pathogenesis-related protein (PR-5)). Conclusions: Grass pollen components were identified as the most common inhalant allergen sensitiser. The most common pollen-food cross-reactive component sensitisation was to CCD, which is in keeping with the high level of grass pollen sensitisation. HDM-component sensitisation was lower than expected when correlated with previous studies using whole allergen specific IgE sensitisation data. This study contributes to understanding allergen sensitisation patterns in South Africa by adding component sensitisation data to the current diagnostic knowledge pool; and it raises awareness of the extent of allergen-component cross-reactivity in South Africa.